The present invention relates to a fuel pump for pumping fuel such as gasoline, light oil and heavy oil from a discharge port.
In a known form of fuel pump, a pump section and a motor are assembled as a unit, and fuel is sucked from a suction port into the motor and is discharged from the discharge port. In the fuel pump of this type, there occurs a problem of wear of a commutator. To solve this problem, a brushless motor has been utilized as disclosed in Japanese Laid-Open Patent Publication No. 56-88982.
In operation of the brushless motor, it is necessary to provide an electric circuit for detecting an angular position of a rotor, deciding which coil of a stator is to be excited according to the detection, and switching on and off the excitation of the coil according to the decision. It will be noted that at least a rotor position detecting device must be incorporated in the fuel pump. Further, for ease of handling, it is preferable to incorporate the entire electric circuit including the rotor position detecting device in the fuel pump. However, in incorporating the entire electric circuit in the fuel pump, installation method of the rotor position detecting devices and oil resistance of the electric circuit have to be considered.